Question

x-y = 10
x+y = 4y

Solve that by elimination:

Answer 1

Answer:

For 2 equations, you need to either eliminate one or substitute one into another.

By elimination: (eliminate y from the equation)

Add both equations together.

x+y+x-y = 10+4

2x=14

x=7

Then substitute the value of x into any of the equations.

7-y=4

y=3

By substitution:

From one equation, x+y=10

so x=10-y

Substitute this equation into the other one.

(10-y)-y=4

10–2y=4

2y=6

y=3

Then substitute the value of y into the equation made.

x=10–3=7